Dielectric heating with rotatory work-receiving element



P D NEWHOUSE 2,644,073

DIELECTRIC HEATING WITH ROTATORY WORK-RECEIVING ELEMENT Filed April 1,1949 INVENTOR .PAUL D. NEWHOUSE.

2 Sheets-Sheet 1 ATTORNEY June 30, 1953 WITNESSES:

Patented June 30, 1953 UNITED STATES PATENT OFFICE DIELECTRIC-HEATINGWITH ROTATORY" WORK-RECEIVING ELEMENT Paul D". Newhous'e; Salix, Iowa,assignorto'West inghouse Electric Corporation, East Pittsburgh; Pa.,. acorporation of Pennsylvania Application Aprilil, 1949, Serial No. 84381.

3 Claims:

Broadly; my invention relates to-means' for the invention, the work ormaterial is carried inside a rotatory element through a radialhigh-frequency field produced bystationary electrodes that have nophysical contact with the rotatory element. of eliminating the need forsliding orrolling contacts, brushes etc., whichcausearcing-and energylosses, and are otherwise troublesome;

A general object'ofmy'invention isto provide a means of a type;described for the; dielectric heating, for any purpose; of*'non-gaseousfiuidic' material; and a particular-"object in this connection istoaccomplish such heating on a continuous mass-production basis;

A further object of my invention is to provide a dielectricheatingsystem of a type: described in which a radially-extendingelectric field is provided at the inner surface of a rotatingtubularmember or container bymeans ofan inner electrode on'the inside ofthe tubular member or container, the" electrode" being insulated.there.- from.

Another obj ect of my invention is" to' provide a dielectric heatingsystem of atype' described in which the radial field is established by-astationary electrode inside a work-receiving container, and anotherstationaryelectrode'outside of the container. The container has a wallwhicheholds the work to'be heated, and all'or a portion'of this wallmoves'betweenthe two stationary electrodes as it-rotates.v The containerisof metal, and is capacitively coupled to the outer electrodeforfeeding electrical energy into the work. tubewhich completelysurrounds the container and by grounding this outerielectrode, a highdegree of safety for operatorsofthe-apparatus is obtained.

Objects, features and innovations of my invention, in addition to theforegoing, will. be. discernible from the following description ofseveral preferred forms thereof. to betaken in conjunction withtheaccompanying'drawings in which details not essential toan Such astructure has the advantage- By making the. outer electrode a Thisdescription is understanding oftheinventionhave beenomitted in theinterests of simplicity and clarity; In" the simplified drawings, whichare not to scale, Figure 1 is a vertical axial sectional viewofanembodiment of my'invention;

Figs. 2' and 3' are sectional views alongthe lines II'II and III--III,'respectively, of Fig. 1;

Fig. 4 is a vertical sectional view; corresponding to Fig. 2', ofanother embodiment of myinvention;

Fig. 5 is a vertical'sectlonal view'ofa further embodiment of 'my'invention;

Fig. 6 is a; horizontalse'ctional view on the'lin'e VI--VI of Fig. 5;and

Figs; 7' and 8 are: partial vertical sections of further modificationsof my invention;

The broader aspects of" mybinvention can find expression in manydifierentembodiments, each constituting a newand useful improvementinits' In this application, my invention is own right.

shown in severalforms. One comprises a rotary kiln comprising a tubularmember throughwhich discrete solid particles are passed for dielectricheat-treatment. of a drying centrifuge. Still another form of myinvention which utilizes rollers between which sheet material moves; isdescribedand claimed in my copending' application'Serial'No. 84,882;filed concurrently herewith.-

Figs. 1 through-4 show myinvention' embodied in a rotarykiln=typeapparatus. Work or mat'erial 2 'in' the form ofdiscreteparticlessuch'a's', byway of exampleon'ly; grain'particles', is slow 1y fed froma hopper its the upper'open end'of arotatory work receiving' member ortumbler having a wall in the form of a tube or'tubula'r' member 6' ofmetal. The other end of tumbler tubular member Bhas an insulating plateSsesupporting means comprisesa shaft'l2 secured to the-center oftheinsulating plate 8 and a bearing or bearings. It for the shaft.The'shaft l2 isrotatedby anysuitabledriving means; The tumbler tubularmember 6S constitutes a Workreceiving container and has ahelicallwork-guide E6, of exceptionally low-loss insulation," secured'to its inner surface for assuring downward movement of particles ofmaterial 2 fed to the member $5 from the hopper '4. Similarly, spacedinsulating longitudinal tumbling strips I! can be.

secured to the insideof the tumblenbetween'th'e turns of the work=guidel6; Material passing A further'form is inthe'nature' aeaaovs through thetubular member 6 discharges therefrom through openings ill and fallsinto any suitable work-receiving means it.

A high-frequency electric field is established through the work-carryingportion along the lower side of the tumbler tubular member 6, throughmeans comprising an inner electrode 22 and outer electrode 2 The innerelectrode comprises a curved metal plate 2t carried by an insulatingsupport 28 that includes a rod 29 that passes through the upper open endof the tumbler tubular member 5. This rod may be fastened to anysuitable structure that holds the support 253 and the electrodestationary inside the tumbler tubular member so that the curved plate ofthe electrode 22 is spaced from the tumbler tubular member 5. Bystationary, I do not mean absolutely fixed with respect to the ground,since I contemplate adjustably positioning the plate inside the tumblertubular n1ember at different distances from the tumbler tubular andeither substantially conor coat al therewith or with its axis at anangle therewith.

The outer electrode it also comprises a curved member in the form of astationary metal that completely encompasses the tumbler 1 rneznber Thistube Eli] is also concentric the tubular member 8. The nested room h s,comprising the inner plate lit, the outer e -lll and the intermediatetubular member electrically insulated from each other, and to give anysuitable spacing between them.

he upper part or the inner electrode 22 can 'ovided with a pair ofinsulating boards W or proper length to form a tent or dihedral angleover the hollow portion of the curved 3 so as to prevent that ride :pthe tubular member 6 from falling into the hollow portion of the curvedplate of the electrode Highrequency energy is supplied to the electrodes22 and Ed by any suitable means. For ex ample, it may be applied. bymeans of a transmission linecomprising a coaxial cable having an outergrounded conductor it and an inner insulate-d conductor 3. The insulatedconductor is directly electrically connected to the insulated metalplate of the inner electrode 22. grounded conductor is electrically connected to the tube SE of the outer electrode 2 5, either directly orthrough ground, the tube being shown grounded at A tube-oscillation generator (not shown) can be connected, through any suitable controlapparatus, to the coaxial cable as a source for the high-frequencyenergy, which for dielectric heating usually has a frequency in theorder of inegacycles. The outer electrode capacitively coupled to thetuinbler tubular n oer through the air space between them.

'en the electrodes 22 and M are energized, li ireauency voltage existsacross them and an electric hold is provided that passes radiallythrough that lower portion of the tumbler tubular znei'nber El whichhappens to be between the facing parts of the plate and tube oftheelectrodes. The radial electric field thus provided dielectricallyheat-treats particles of material they move downwardly during therotation of the tumbler tubular member 6.

An important feature of my invention resides in the fact that no directelectrical connection is required between the tumbler tubular member sand either of the electrodes 22 and 24 in order to establish a radialfield inside of the tubular member, that passes through the lowerworkcarrying portion thereof. Also, by grounding the 5 tube til of theouter electrode 24 and by having it substantially completely encompassthe turnbier tubular member 6, the high-potential parts of thedielectric heating apparatus described are well screened, and a highdegree of safety is assured for operators around the apparatus.

Fig. i represents a modified form of apparatus which correspondssubstantially to that described in connection with Figs. 1. through 3,except that the inner electrode is made in the form of a com" pletemetal tube 4:2 instead of a partly cylindrical metal plate, such asplate Such construction will provide a complete radial electric fieldaround the full inside surface of the tumbler tubular member Fig. 5shows a drying centrifuge embodying the principles of invention.Referring to this figure, the rotatory work-receiving tubular membercoin rises a pair of nested or concentric rents or walls 52 and that areride a work-receiving space in which non-gaseous fiuidic work ormaterial 56, such for silica gel to be dried, or cloth material to bedried, is received. An annular bottom. lid of nsulation closes the spacebetween the inner tubular element 552 and the outer tubu" lar ele .cn;is carried on insulating disc is which is ro tatably carried on a hollowshaft 52 journalled in a bear or bearings When the hollow shaft ted, itis evident that the ubular mernb s also rotate at a speed depending onthe rotational or the shaft The shaft be driven at desired speed by any.ble means.

. space of the tubular i on ved. el ctrodes E8 and the former beinginside the r and the latter outside of it. The inc-er and outer curvedelectrodes 58 and respect ly can be supported in any suitable manner soas to be concentric with but sta tionary with respect to the rotatorytubular member The support trode cor.

v means shown for the inner elecprises a stationary shaft that passesupwacuy through the hollow rotatable shaft i'he shaft extends upwardlybeyond. the insulating disc carries eross-bars l2 which, in turn, carrythe inner electrode 66 which is in the form of a tube is but obviouslycan be some other shape. The outer electrode 68 is in the fOllll of ametal tube 35 that is car-- For supplying high-irevoltage acrosselectrodes {36 and 68, nsinission line is connected to the electrodes,insulated conductor i362 detachably se inner electrode rat, and groundedconductor i i electrically co;..nected to the tube of tr e outerelectrode it through a suitable connection, shown as a ground connection85.

The rotator tubular member to constitutes a work-receiving container orcage which is the only rotating or" the apparatus except for the drivingshaft and the supporting means from. the shaft to the tubular member.The highvoltage electrode lit on the inside of the container ispractically entirely surrounded by material o Wu.

5 being processed and by the grounded outer electrode 68.

The tubular elements or walls 52 and 54 of the tubular member 59 can beconstructed in any desired manner suited to the purpose to which myinvention is applied, which may be drying, centrifugal separation, orany other purpose for which centrifuges or rotatory tubular members arecommonly used. An apparatus of the type shown is especially suited fortreating viscous materials, such as, for example, oil from which Wateris to be removed, etc. The viscosity of highly viscous materials isreduced with heat, and vapors are driven off which can be removed by anair blast 68 which blows air upwardly through the space between theouter tube 76 and the outer tubular element 54 of the rotatory tubularmember 56. To permit this use of the apparatus, the inner tubularelement 52 can be made from sheet metal, and outer tubular element 5dcan be made from a metal screen or perforated sheet metal that allowseasy passage or liquid or vapor. If desired, the outer tubular member 76of the outer electrode 69 can also be made from metal screening or theequivalent. Copper or aluminum is recommended for the metal parts of theapparatus, unless either reacts with the material being processed. Insuch case, any other suitable low conductivity metal or plated metal canbe used. Obviously, for heating liquids the two tubular elements 52 and54 of the tubular member or container 50 should be solid.

In order to permit the container to be easily loaded and unloaded, theinsulation disc 69 that supports the tubular member 59 can be providedwith an annular seat 99 in which the tubular member removably sits sothat the member can be lifted out of the apparatus whenever desired, andthen restored.

For best electrical eiiiciency, the voltage across the space or spacesbetween the stationary and rotating parts should be as low as possibleso that most of the voltage supplied by the generator appears across thematerial being heated. Figs. 7 and 8 show improved means for raising theproportion of voltage across the useful load with respect to the voltagerequired for the capacitive coupling.

In Fig. 7, the rotating insulating disc I00 carries a work-holdingtubular member 192 com.- prising a metal outer tube 16:1 and a metalinner tube I96. The stationary parts comprise an outer set of concentricmetal tubes Hi3 and I I0, which are grounded, and an inner set ofconcentric metal tubes i I2, 5 E i and I Hi which are connected to aninsulated high-voltage high-frequency conductor H3.

Unitary with and electrically connected to the outer tube I64 of thework-holding member I02 is a metal tube I22. The tube I22 is concentricwith the tubes 108 and H0 and rotates between them. Similarly, the innertube I96 of the workholding member 2 t2 is provided with nested metaltubes 12d and [26 to which it is electrically connected. The tubes i241and 126 rotate between the tubes H2, H6 and [16.

In cases where it is not necessary to remove the work-holding containerfrom the disc, the capacitiv coupling for providing a voltage across theinner and outer tubes of the rotating container can be arranged as shownin 8. In Fig. 8, the stationary electrodes I39 and I32 are provided withannular plates 16 and 836 which interleave similar plates 138 and M0 ona rotating work-holding container :42.

While I have described my invention in forms which are now preferred, itis obvious that its principles can be applied in other forms andmodifications.

I claim as my invention:

1. Dielectric heating means of a type described comprising, incombination, a pair of spaceyl, upstanding substantially-coaxial,stationary, relatively-insulated, metallic curved electrode-members, anannular-like container substantially coaxial with said electrode-memberscomprising a plurality of wall members, said-container being positionedbetween said electrode-members, support means for rotatably supportingsaid container between said electrode-members and insulated therefrom,and means for applying a high-frequency voltage across saidelectrodemembers.

2. An invention including that of claim 1, but further characterized bysaid container comprising a pair of nested upstanding walls, adapted tocontain a non-gaseous fiuidic material, that pass between saidelectrode-members as the container is rotated.

3. An invention including that of claim 1, but further characterized bysaid container being removable from between said electrode-members.

PAUL D. NEWI-IOUSE.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,954,273 Subkow Sept. 15, 1936 2,167,718 Harris Aug. 1, 19392,231,457 Stephen Feb. 11, 1941 2,403,800 Hoyler July 9, 1946 2,472,193Clayton June 7, 1949 2,473,881 Hagopian June 21, 1949 2,479,351 HagopianAug. 16, 1949 2,501,776 Kuljian Mar. 28, 1950 2,512,604 Bierwirth June27, 1950 FOREIGN PATENTS Number Country Date 609,192 Great Britain Sept.27, 1943 986,860 France Aug. 6, 1951 517,798 Great Britain Feb. 8, 1940

